Stem cells are known to have a remarkable potential to develop into many different cell types in the body during early life and growth.1 They also serve as internal repair systems for some tissues to replenish other cells as long as the organ-carrier (humans, animals) is still alive. The combination of stem cells with polymeric scaffolds is a promising strategy for engineering tissues and cellular delivery.2 Several types of scaffolds have been used in combination with stem cells for tissue engineering applications. Such scaffold materials can generally be classified as natural or synthetic and each have distinct advantages and drawbacks.3 
Several natural or biocompatible synthetic materials have been developed for specific scaffold applications, and many are based on proteins (fibrin, silk), polysaccharides (agarose, alginate), polymers (e.g., PEG), peptides, or ceramic materials. Depending on their chemical nature these types of scaffolds have been studied for bone, cartilage, heart, nerve, retinal and vasculature tissue applications, and can involve directed differentiation of stem cells into mature phenotypes or using the biomaterial scaffolds for expansion of undifferentiated stem cells. None of these approaches, however, has yet demonstrated the use of biocompatible scaffolds that can, by choice, respond to a variety of external stimuli such as temperature, applied fields (electric, magnetic), surface alignment, or mechanic deformation (stress/strain) with a macroscopic ordering event (an increase in order), i.e. a smart responsive scaffold (or SRS).
The advantages of using cell delivery for therapeutic applications are without doubt of significant relevance; it is however the administration methods that are an important key for the success of the treatments sought, such as injecting dispersion of cells directly into injured sites.4 Other approaches were to encapsulate cells in polymer matrices. Hydrogels were thought to be attractive due to their potential in maintaining cell viability; however they do not offer the necessary mechanical support.5 Alternative approaches have focused on the use of porous beads for the purpose of cell delivery. Here, beads are cell-loaded and cultured in medium prior to being placed or injected directly into the affected or diseased site.6 While beads and hydrogels can also contain bioactive agents (growth factors, proteins) they do not guide cells to differentiation into a particular cell lineage. Extreme care should be taken in the choice of cells to be implanted. In this respect, it is of paramount importance to ensure that cells will differentiate into the desirable lineage by ‘copying’ surrounding cells. If there is heterogeneity of cells at the sites sought for repair, it will ultimately be difficult to predict that cells will respond as desired. Some scaffolds made of natural polymers (fibrin or collagen) have been proven difficult in the area of tissue regeneration because of the necrosis (cell death) found at the center of these scaffold.7 In addition, these scaffolds presented diminished mechanical properties and instability.
Elastomers, however, have gained considerable attention because they offer many advantages over tough rigid polymers. Most importantly, the physical properties of elastomers can be tuned in a way that they can withstand mechanical tasks such as strain, stress, and impacts because they are soft and deformable.8 They have also been found suitable as carriers for drug delivery applications. Biodegradable elastomers have been mainly made of two types; thermoplastics9 and thermosets.10,11 Thermoplastics are easily made; however, they degrade heterogeneously because of the presence of crystalline and amorphous regions within the material leading to a rapid loss of mechanical strength. While thermosets are not as easily prepared, they do offer more uniform biodegradation rates, better mechanical properties, and chemical resistance. Hence, thermoset elastomers based on three-arm star block co-polymers (SBCs)10,12 using ring opening polymerization of the suitable monomers followed by cross-linking to form an elastomer are the materials of choice for the preparation of SRS materials.